never ever over the fact that they were holding hands in tbb

Irene Adler is a Mirror for both Sherlock and John, depending on which character is viewing her in ASiB.

We’ve all noticed the overwhelming similarities between Irene and Sherlock - it’s frankly rather hard to miss them.  Wavy brown hair, blue eyes, amazing cheekbones, use of a riding crop, their cleverness, their sexual orientation… we could go on for an hour about this.  It’s so obvious to us to see their connection because we are watching S2 through John’s POV.  He sees Irene as a Stand-in for Sherlock.  Whenever John is an outsider looking in, he sees those two mirror each other.  However, the same can be said for Sherlock who sees Irene mirror John, whenever he’s an outsider looking in.  Therefore, every interaction these characters have with one another in ASiB has ulterior meaning depending on who the onlooker happens to be.  The goal of this post is to make it easier for viewers to switch POVs in this episode to find out exactly what Irene means to these two men and the long-term effect she has on their romance.  

Let’s start with John’s POV because it’s easier.  He meets Irene and is professional, but confused.  Once she puts on Sherlock’s coat, John starts to flirt (You like policemen? / I like detectives).  She and Sherlock have a small battle of wits and John leaves the room.  To John, he sees Irene from the beginning as similar to Sherlock.  Later Irene drugs Sherlock (Something only Sherlock does to himself) and she vanishes.  John counts all of the texts she sends Sherlock, remarking on how often she reaches out.  He later remarks about how Sherlock always replies to everything and always needs the last word, so John believes Irene is the same way, texting Sherlock incessantly because they both always need the last word.  Once Irene dies, John sees Sherlock wilt.  To him they are one and the same.  The day Irene breaks into the flat in order to get Sherlock’s help with the Bond Air email, John is watching the two of them battle their cleverness in perfect harmony.  Irene is wearing Sherlock’s dressing gown.  John interjects his middle name in order to include himself in what appears to be two people becoming one.  And if they were to literally become one, John thinks they should name the child after him. John leaves Sherlock and Irene alone that night, tired of being an outsider since the two of them have so much in common.   And this is exactly how the viewers are supposed to see Irene - a clever woman battling a clever man.  Irene+Sherlock with John by himself.  At least, this is what the episode looks like if you’re only examining the actions between Irene and Sherlock through John’s POV.  

Sherlock’s POV is so much more important than John’s in ASiB because we see everything Sherlock thinks regarding a possible romance with John play out in this episode.  This is a little trickier so bear with me.  

Sherlock has been thrown off his game ever since John offered to die for him at the pool.  Sherlock’s obsessed with finding out John’s middle name, he’s smoking again.  Sherlock is fully invested but doesn’t know if John feels the same way.  Remember John told Sherlock in ASiP that his deduction about John asking him out at Angelo’s was wrong.  Sherlock has conceded that he must’ve misjudged John’s intentions.  Ever since then he’s been trying to figure out how to gain more information on this topic.  He offers John money in TBB as a kind gesture, also tells him not to get a job so he can hang with Sherlock more often.  Sherlock has nothing to go on regarding reading John’s intentions until he meets Irene Adler.  From the beginning Irene is seen through Sherlock’s eyes as a mirror for John and once he overhears her confession at Battersea, he takes to treating her like he would John, as practice for gaining more information about what it looks like when someone falls in love. Because he needs to know once and for all what John thinks about him romantically. 

First Sherlock is made aware of Irene through her website.  She, like John, advertises her services this way.  While John’s website is fully devoted to Sherlock, Irene’s is fully devoted to sex.  Once in Irene’s sitting room, Sherlock watches John and Irene flirt which causes him to jumble and slur his words.  He quickly recovers and plays it off as nothing.  He saw those two bond over something sexual without him.  He changes the subject to break the two of them up.  Irene breaks into Sherlock’s bedroom and once he wakes up and remembers what happened, he calls out to John.  John and Irene are the only two we see ever from Sherlock’s POV in his own bedroom.  Sherlock follows John to Battersea and listens to the conversation Irene has with him.  This is where we see just how similar John is to Irene: regardless of their assumed sexual orientation, they are both in love with Sherlock. John doesn’t deny this, by the way.  John and Irene are one and the same, in Sherlock’s mind.  This is why he tells both of them “Happy New Year”.  If Irene does in fact love Sherlock, then he can see if John does in fact love him, as well.  That means treating them both equally.  Once Irene shows up in his flat, he does his impressive deductions because he knows that works on John.  And it works on Irene, too.  Every time things go in a sexual direction, Sherlock always reaches out to bring John into the conversation.  Sherlock needs both of them to continue to mirror each other if he’s going to figure anything about John’s feelings for him.  

Later in the evening John leaves Irene and Sherlock alone.  Sherlock has no idea and continues talking to John, even though it’s Irene who’s listening.  He swapped those two characters in his own mind because from his POV they are one and the same.  Irene comes on to Sherlock and he appears confused at first.  However, he allows things to escalate once he takes hold of her wrist.  He knows then what she’s possibly looking for and he’s willing to play the part a little longer in order to get a legitimate example of what it means scientifically when one person falls in love.  He notices her pupils dilate and her pulse elevate.  He took that information and stored it.  He wasn’t trying to uncover her password - that he figured out later on accident.  He was taking note of her biological responses for another reason: to use that information to find out if John reacts the same way. 

This is why Sherlock approaches John in the kitchen at the end of the episode and stands uncomfortably close to John.  He’s there to take note of John’s pupils and heart rate.  And he finds that John responds just as Irene did. Because when it’s Sherlock’s POV, John and Irene are mirrors.

SO THE BIG QUESTION WE MUST NOW ASK: Is Sherlock’s end speech to Irene about the devastating effects of love meant for Irene? The answer is no.  Sherlock sees her come so close to having everything she could possibly want in this world, but her love for Sherlock destroyed her chance at safety and happiness.  Sherlock scolds her for getting too caught up in love.  If Sherlock hadn’t made it to Karachi, her love for him would’ve gotten her killed. This is exactly why he went to save her in the first place - her death would be on his hands since he was the one whom she loved, the one who lead to her downfall.  Sherlock could never let that happen to John Watson.  Sherlock could not live with himself harming John’s safety and happiness.  John cannot be a mirror for Irene any longer.  

Sherlock, now aware of what he must do, finds out from his biological signs that John does love him.  Sherlock retrieves the cell phone from John, symbolically taking his heart and putting it away.  Sherlock turns his gaze away, back to his microscope.  Sherlock will not stand for John continuing to follow in Irene’s footsteps.